TDD is a progressive approach. It comprises TFA and refactoring (Regression testing).
This can be expressed in form of a equation:
TDD = TFA + Refactoring
When should we test a Database
The process of refactoring here means a small change to a database schema, which improves its design without changing its semantics. It is an evolutionary improvement of our database schema, which will further support following three things:
1) New needs of our customers.
2) Evolutionary software development.
3) Fix legacy database design problem.
Many More Articles & Tutorials on Databse Testing